Apparatus for conducting washing operations in a well



y 1952 J. R. JACKSON ET AL 3,032,118

APPARATUS FORICONDUCTING WASHING OPERATIONS IN A WELL Filed Oct. 11. 1957 2 Sheets-Sheet 1 INVENTORS J. R. JACKSON J. H. MARSEE F/G. FIG. 2.

BY MTM ATTO NEYS.

y 1962 J. R. JACKSON ETAL 3,032,118

APPARATUS FOR CONDUCTING WASHING OPERATIONS IN A WELL Filed Oct. 11. 1957 2 Sheets-Sheet 2 F/G. 5 F/G. 4

v has INVENTORS J.R.JACKSON BY J. H. MARSEE United States Patent Ofifice 3,032,118 Patented May 1, 1962 3,032,118 APPARATUS FOR CGNDUCTING WASHING OPERATIONS IN A WELL James R. Jackson, Fort Stockton, Tex., and Jack H.

Marsee, Tulsa, Okla, assignors to Phillips Petroleum Company, a corporation of Delaware Filed Oct. 11, 1957, Ser. No. 689,544 12 Claims. {CL 166-243) This invention relates to apparatus for conducting operations in a well. In one of its aspects, this invention relates to apparatus for conducting washing-over operations in a well. In another of its aspects, this invention relates to apparatus for conducting internal Washing operations in a well. In another of its aspects, thi invention relates to apparatus for conducting fishing operations in a well.

The usual practice for the recovery of drill pipe which has become stuck or lodged in the drill hole comprises establishing the free point by the use of a free point indicator and then backing off on the drill pipe at the instant a string shot is set oil? adjacent the nearest drill pipe connection above the free point to thereby free the drill pipe above the point at which it is stuck in the drill hole. The freed drill pipe is withdrawn and wash pipe is then run into the hole and the stuck drill pipe washed over in an effort to free it. Frequently, the wash-over process results in the bore of the stuck drill pipe becoming plugged with debris which prevents running another string shot for loosening that portion of the stuck drill pipe which was otherwise freed in the wash-over process. Sometimes, the obstruction in the bore of the drill pipe can be removed by running a spud bar on the shooting line. Also, the bore of the drill pipe and collars can sometimes be cleaned out by running in a hydrostatic bailer on the shooting line. The more, positive method of removing the obstruction from the bore of the drill pipe comprises running a string of small diameter pipe or macaroni tubing inside the drill pipe and then washing the obstruction out of the drill string bore. This latter method is very time consuming and is also very risky, particularly Where the well is very deep, since the drill pipe may have become stuck during the time the small diameter pipe is being run into the well and because the small diameter pipe is structurally weak and prone to loss in the well.

An object of this invention is to provide an improved apparatus for recovering and removing pipe, tubing or the like from a well bore hole.

Another object of this invention is to provide an improved apparatus for conducting internal washing operations in a well bore hole and subsequent recovery of the fish without removing the fishing tools from the fishing string.

Another object of this invention is to provide an improved apparatus for telescopically extending tubing in a well bore hole.

Another object of this invention is to provide an improved apparatus for readily running a washing means into a Well bore hole on a wire line without extended frictional contact of said washing means with tubing in said well bore hole.

Other aspects, objects and the advantages of the invention are apparent from a consideration of the accompanying description, the drawings and the appended claims.

According to the present invention, there is provided an apparatus for conducting operations in a well bore hole where it is necessary to remove sand, cement, debris, fish, including tubing, and the like, from said well bore hole. The apparatus comprises, as one part, a string of an internal flush joint tubing of fixed length carried in the lower end of the fishing string or other tubing to be lowered into the well bore hole for the purpose of recovering fish and conducting washing operations. The apparatus of this invention also comprises, as another part, an internal washing tool of small diameter wash tubing or macaroni tubing of fixed length having a sealing means attached to one end and adapted to be lowered into said well bore hole by Wire through the fishing string into the internal flush tubing carried in the lower end of said fishing string to be slidably engaged with said internal flush tubing and to be extended telescopically into the well bore hole below the lowermost end of the fishing string. The diameter of the sealing means attached to the outside of the fixed length of the macaroni wash tubing has a diameter less than the internal diameter of the fishing string so that little frictional resistance is encountered in loWering the macaroni wash tubing through the fishing string. The external diameter of the internal flush tubing is less than the internal diameter of the fishing string. The relationship of the diameter of the sealing means attached to the macaroni wash tubing and the internal diameter of the internal flush tubing is such as to effect a seal in the annular space between the external surface of the macaroni wash tubing and the internal surface of the internal flush tubing. A special sub attached to the lower end of the fishing string is employed to arrange the internal flush tubing concentrically within the fishing string.

The apparatus of the invention can be utilized for con ducting fishing operations in a Well bore hole, including washing operations, such as internal washing of fish, in one trip of the fishing string into the well bore hole. In conducting these operations, a fishing string containing a length of internal flush tubing in its lower end and carrying the necessary fishing tools and wash-over tools is run into the Well bore hole into contact with the fish. Washing over of the fish is accomplished in the normal manner by circulating washing fluid into the well bore hole through a fishing string around the fish, and out of the well bore hole through the annular space existing between the fishing string and the Walls of the well bore hole. When wash over operations are completed, the wash over tools are removed and the apparatus of the present invention is installed on the lower end of the fish ing string so that internal washing of the fish is accomplished by running an internal Washing tool into the fishing string on a Wire line free from frictional contact with the inner wall of said fishing string. The internal wash ing tool, comprising a fixed length of small diameter or macaroni wash tubing having a sealing means on its uppermost end, slidably engages the internal. flush tubing in a fluid sealing relationship and is telescopically extended through the lowermost end of the fishing string into the fish by regulation of the pressure of the circulating washing fiuid. Upon effecting the internal removal of debris, sand, cement, and the like, from within the fish, as determined by the pressure maintained on the circulating washing fluid, the internal washing tool is removed from the well bore hole by means of the wire line. Then without removing the fishing string from. the Well bore, it is joined to the fish, as by screwing together, a string shot is lowered into the fish to a point opposite the lowermost point of the wash over operation and exploded opsesame posite a threaded connection so that the threaded connection will be loosened for subsequent unscrewing and removal of part of the fish by withdrawing the fishing string from the well bore. This operation is repeated as necessary until all of the fish has been removed from the well bore.

The invention is further illustrated by the accompanying drawings. FIGURE 1 shows the internal washing tool of the invention removed from the well bore hole. FIGURE 2 is a sectional view of the lowermost portion of a fishing string or other tubing containing the internal flush tubing and special sub attached thereto. FIGURE 3 is a sectional view showing the operation of the invention in a Well bore hole. FIGURE 4 is a sectional view showing how a wash-over tool can be connected to the special sub of FIGURE 3. FIGURE 5 is a sectional View showing how an overshot tool and a wash-over tool can be connected to the special sub of FIGURE 3.

Referring to FIGURE 1, internal wishing tool comprises a fixed length of small diameter Wash tubing 11 which is a tubular member having a lower open end 12 and an upper end 13 closed by a sucker rod connector 14. Lateral openings 15 are provided through the wall or wash tubing 11 adjacent the closed end 13 to permit the flow of fluid into wash tubing 11 at the top thereof. Multiple packers 1e are mounted on tubing 11 adjacent closed end 13 and below lateral openings 15. A wire line 17 is attached to internal washing tool -10 by means of sucker rod connector 14.

Referring to FIGURE 2, a string of internal flush joint tubing 18, which is a tubular member having a diameter somewhat smaller than the diameter of drill pipe 19, is mounted concentrically within drill pipe 19. Theconcentric mounting of internal flush tubing 18 in drill pipe 19 is secured by first attaching the lower end 29 of internal flush tubing 18 into a special sub 21 by means of screw threads 22 and then attaching special sub 21 to drill pipe 19 at pipe joint 23 by means of screw threads 24. Weld 25 is placed between the outside of internal flush tubing 18 and the internal wall of special sub 21 in order to rigidly fix internal flush tubing 18 into special sub 21. Special sub 21 has a centrally disposed circular bore 26 of a diameter which is less than the internal diameter of internal flush tubing 18 but greater than the external diameter of small diameter Wash tubing 11. Upper end 27 of internal flush tubing 18 is outwardly flared to form a funnel shape.

In FIGURE 3, the cooperation betweeninternal Washing tool 10 with internal flush tubing 18 carried in the lower end of fishing string 19 is shown in a well bore hole. As shown in FIGURE 3, additional drill pipe 28 has been attached to the upper end of drill pipe 19 by means of pipe joint 29. Special sub 21 terminates in threaded portion 34 adapted to engage threads 35 in fish 31. Upon completion of the internal washing operation, threaded portions 34 and 35 will be screwed together by rotation of pipe 28 to aid in the ultimate recovery of the fish 31. It is to be understood that threaded portion 34 can be attached to any conventional overshot with unobstructed central passageway so that fish 31 can be grasped from the outside if such is necessary. However, for purposes of illustration, the cooperating threads 34 and 35 only are illustrated since no other attachment means will be required in many situations arising in oil well drilling operations.

For conducting internal washing within fish 31, as shown in FIGURE 3, internal washing tool It is lowered by means of Wire line 17 through drill pipe 23 into internal flush tubing 18, the funnel shaped portion 27 serving to guide washing tool 18 into internal flush tubing 13. A fluid seal is readily effected between multiple packers 16 and the internal wall of internal flush tubing 18 through means of the flared end 27 so that the only path of flow for wash fluid from drill pipe 28 is through later'alopenings 15 into the passageway within wash tubing 11 of internal washing tool 10 and thence through the lower end 12 of wash tubing 11. It is seen that internal flush tubing 18 functions as an elongated internal sealing member with packers 16 in sealing relation therewith. As the internal washing operation within fish 31 is conducted, internal washing tool 10 is lowered into the well bore hole in order to keep the lower open end 12 of internal Washing tool 1% adjacent the debris to be removed from within fish 31. In this manner, the internal wall of internal flush tubing 18 comprises an elongated sealing surface when multiple packers 16 are contacted therewith so that the flow of wash fluid is confined to the internal passages of fish 31. Wash fluid is circulated through wash tool 13 down inside fish 31 and the wash fluid carrying debris is returned outside the wash tubing 11 and is then brought to the surface of the ground through the annular space between drill pipe 28 and surface of the well bore hole 32. It is impossible for internal washing tool 10 to be dropped through the lower end of special sub 21 because the internal diameter of bore 26 in special sub 21 is less than the external diameter of multiple packers 16.

The specific length of small diameter washtubing 11 making up internal washing tool 10 is determined by the length of stuck tubing to be cleaned out. Ordinarily, the length of internal washing tool 10 and internal flush tubing 18 is in the range of about 20 to 100 feet. The lengths of internal washing tool 10 and internal flush tubing 18 are approximately equal in the usual operation; however, these lengths may be considerably different and either may be longer or shorter than the other, depending upon the distance of the top of fish 31 to the top of the debris within fish 31 and the depth of the debris within fish 31. The length of small diameter Wash I tubing 11 in internal Washing tool 10 is limited by the breaking strength. of the wire line used to lower the internal washing tool into the Well.

FIGURE 4 illustrates how a wash-over tool or pipe 36 can be aifixed to the special sub 21 of FIGURE 3, for example, by means of welding. The wash-over tool 36 has an inner. diameter larger than the outer diameter of fish 31 and, as shown in the drawing, wash-over tool 36 surrounds the upper portion of fish 31. The lower end of wash-over tool 36 can be provided with a plurality of circumferentially spaced cutting edges 38. To wash-over a fish, the washing fluid is pumped down drill pipe 28, through internal flush tubing 18, bore 26 of special sub 21, and down through annulus 37 between fish 31 and wash-over tool 36, the drill pipe being rotated when necessary to free the fish from debris, sand, and the like, which tend to stick the fish. After the washing, operations, the wash tool 11 can be lowered to washout the debris from the inside of the fish. Following the internal washing of fish 31, the drill pipe can be lowered so as to permit the threads 34 of special sub 21 to engage the threads of the fish, thereby allowing the removal of the fish from the well here.

A conventional overshot can also be connected to the threaded portion 34 of special sub 21. This is illustrated in FIGURE 5 where conventional overshot 39 is affixed in this manner. This overshot 39 comprises an upper coupling 41 connected to threaded portion 34 of special sub 2.1, and a tubing 42 connected by threaded portion of coupling 41. The lower end of the overshot tool tubing 42 is connected by threads to wash-over tool 36, which is like that of FIGURE 4. Overshot tubing 42 is internally provided with an annular slip retaining ring 43. A compression spring 44 is interposed between the upper surface of retaining ring 43 and the upper end of bore within coupling 41. Conventional slip 46 is disposed within overshot tubing 42 and held in place by slip retaining ring 43. Slip retaining ring 43 engages slips 46 and under the influence of spring 44 forces slips 46 downward to the catch position. When it is desired to wash-over fish 31, washingfluid is pumped down through drill string 2.8 as before, through overshot tool 39 and annulus 37 between wash-over tool 36 and fish 31. After washing over fish 31, washing tube 11 of this invention is lowered into the well, and the internal washing of fish 31 is accomplished. After washing fish 31, it can e removed by first lowering the entire tool so that the top of fish 31 forces slips 46 upward and outward to allow a fish to enter the slip. Subsequent lifting of the overshot causes slips 46 to grasp the exterior of fish 31 so that it can be removed along with the drill pipe.

To illustrate the operation of the apparatus of this invention, drill collars have become stuck at a depth of 11,833 feet as established by the use of a free-point indicator. The drill pipe was backed off at the nearest connection above the free-point and withdrawn from the well bore hole. After washing-over operations had been completed, a fishing string containing 90 feet of internal flush joint tubing 18 having a 2 inch internal diameter attached to its lower end by special sub 21 was run into the well bore hole into contact with the stuck pipe. Pump pressure was then applied and the resulting pressure increase established the fact that the connections were properly fitted together. The drill string was then raised two and one half inches. Observation of the wash fluid circulation pressure established the fact that there could be no restriction to fiuid flow, while at the same time the string had not been raised sufficiently to completely pad the connections. FIGURE 3 illustrates the relative position of special sub 21 and fish 31 at this stage of the operation. The internal washing tool 10, containing 90 feet of small diameter wash tubing 11 having an external diameter of 1 inch, was run into the fishing string on a wire line 17. Small diameter wash tubing 11 was lowered through internal flush joint tubing 18 and out of the bottom of the fishing string into the collars to be cleaned out. When contact was made with the ob struction in the stuck collars, the pressure on the wash fluid was built up to approximately 300 psig. and the obstruction washed away. As the obstruction in the stuck drill collars was removed, small diameter wash tubing 11 was lowered further into the fish by wire line 17 in order to contact the remaining portion of the obstruction. Thus, the obstruction in these stuck drill collars was removed very efiiciently and safely in approximately four hours, whereas, if the internal washing tool of this invention had not been available, it would have required approxi mately forty-eight hours to run a small diameter or macaroni tubing into the well bore hole from the surface. During this time, the stuck pipe would have become even more firmly stuck and there would be considerable danger in a failure developing in the approximately 11,000 feet of small diameter tubing which would be required to reach the obstruction in the stuck pipe.

While the invention has been described in such a manner as to require that wash over operations be completed before internal washing is begun, it will be apparent to those skilled in the art that it would also be possible to conduct wash over operations in conjunction with the internal washing operation in such a manner as to require only one trip into the Well bore with fishing tools. To do this it would only be necessary to install a wash over pipe of desired length on the lower end of special sub 21, for example, as shown in FIGURE 4 or FIG- URE 5. In such a case, wash over operations would be completed first. Following this, and without removing the drill pipe and fishing tools, the internal washing operation could be carried out and the fish removed as described above.

Another modification that would be readily apparent is the adoption of different sealing means to effect a seal between wash tubing 11 and internal flush tubing l8. As a specific example, sealing rings could be installed in special sub 21 in such a manner that internal flush tubing 13 will retain them in position when said tubing is screwed into threads 22.

While the apparatus of this invention has been described for use in oil Wells, this apparatus can be used in any well bore hole which is made in the earth and where it is necessary to remove fish, debris, sand and the like therefrom. Thus, the apparatus of this invention can be used in other wells, such as brine, gas, or water wells.

Reasonable variation and modification are possible within the scope of the foregoing disclosure, drawing and the appended claims to the invention, the essence of which is that there have been provided apparatus for conducting operations in a well bore hole, including washing-over and internal washing operations, said apparatus comprising (1) an internal washing tool having a fixed length of small diameter or macaroni wash tubing with a sealing member attached to its uppermost end and (2) a fixed length of internal flush joint tubing carried in the lowermost end of a fishing string to be run into the well bore hole, and said internal washing tool being slidably engaged in a fluid sealing relationship with said internal flush joint tubing.

We claim:

1. An apparatus for conducting washing operations in a well bore hole comprising, in combination, a string of tubing adapted to be lowered into said well bore 'hole, a special sub attached to the lower end of said string of tubing, a first tubular member attached at its lower end to said string of tubing by said special sub and mounted concentrically within said string of tubing, a second tubular member of a diameter less than the diameter of said first tubular member, said second tubular member having an opening at each end, an external sealing means attached to the upper end of said second tubular member, said external sealing means having a diameter less than the diameter of said string of tubing and adapted to slidably engage the internal wall of said first tubular member in sealing relations therewith, a wash-over member attached to the lower end of said string of tubing by said special sub, an attaching means on the upper end of said second tubular member, and a wire line connected to said second tubular member by said attaching means for lowering said second tubular member through said string of tubing to a depth such that a substantial portion of said second tubular member is below said special sub attached to the lower end of said string of tubing.

2. An apparatus for conducting washing operations in a well bore hole comprising, in combination, a string of tubing adapted to be lowered into said well bore hole, a special sub attached to the lower end of said string of tubing, a first tubular member attached at its lower end to said string of tubing by said special sub and mounted concentrically within said string of tubing, a second tubular member of a diameter less than the diameter of said first tubular member open at each end, an external sealing means attached to the upper end of said second tubular member of a diameter less than the diameter of said string of tubing and adapted to slidably engage the internal wall of said first tubular member in sealing relation therewith, an attaching means on the upper end of said second tubular member, and a wire line connected to said second tubular member by said attaching means for lowering said second tubular member down said string of tubing and down said first tubular member while in sliding and sealing relation therewith to a depth such that a substantial portion of said second tubular member is below said special sub attached to the lower end of said string of tubing.

3. An apparatus for conducting washing operations in a well bore hole comprising, in combination, a string of tubing adapted to be lowered into said well bore hole, a

special sub attached to the lower end of said string of tubing, a tubular member attached at its lower end to said string of tubing by said special sub and mounted concentrically within said string of tubing, and a wash-over means attached to the lower end of said string of tubing by said special sub. i

4. Apparatus comprising a string of tubing which is lowered into a well bore hole for conducting operations therein, an internal sealing means mounted in the lower end of said string of tubing, a washing tool adapted to be lowered into said string of tubing in place in said well bore hole on a wire line and moved vertically below the lower end of said string of tubing by movement of said Wire line, said washing tool comprising a tubular member of a diameter less than the diameter of said internal sealing means in the lower end of said string of tubing, said tubular member having openings at each end thereof, an external sealing means on the upper end of said tubular member adapted to engage in sealing relation with said internal sealing means in the lower end of said string of tubing during telescopic movement of said tubular member beiow the lower end of said string of tubing, said external sealing means having a diameter less than the diameter of said string of tubing, and an attaching means on the uper end of said tubular member for attaching said tubularmernber to saidwire line.

5. Apparatus comprising a string of tubing which is lowered into a well bore hole for conducting operations therein, an internal sealing means mounted in the lower end of said string of tubing, a washing tool adapted to be lowered into said string of tubing in place in said well bore hole on a wire line below the lower end of said string of tubing, said washing tool comprising a tubular member of a diameter less than the diameter of said internal sealing means in the lower end of said string of tubing, said tubular member having lateral openings in its side wall adjacent the upper end thereof and an open lower end, an external sealing means located on said tubular member adjacent the upper end thereof below said lateral openings adapted to engage in sealing relation with said internal sealing means in the lower end of said string of tubing, said external sealing means having a diameter less than the diameter of said string of tubing, and an attaching means on the upper end of said tubular member for attaching said tubular member to said wire line.

6. In a string of tubing which is lowered into a well bore hole for conducting operations therein, an internal sealing means mounted concentrically within the lower end of said string of tubing, said internal sealing means comprising a tubular body having an external diameter less than the internal diameter of said string of tubing, said body having an outwardly flared upper end, and means on the lower end of said tubular body to attach said internal sealing means to said string of tubing.

7. An apparatus for conducting operations in a well bore, comprising, in combination, a string of first tubing adapted to be lowered into said well bore, a first sealing means mounted Within the lower end of said first tubing and defirn'ng a first passage with a diameter smaller than the inner diameter of said first tubing and in communication therewith, said first passage being substantially in actual alignment with said first tubing, a second tubing having openings in the upper and lower ends thereof and adapted to be suspended within said first tubing and 1ongitudinally moveable therein by means of a wire line, said first and second tubing adapted to form an annular space therebetween, said second tubing having an outer diameter smaller than the inner diameters of said first tubing and said first passage, a second sealing means mounted on the exterior of said second tubing adjacent the upper end thereof, said first and second sealing means adapted to come into sealing relation and seal the lower end of said annular space, and means attached to the lower end of said first tubing and having a second passage therein with a diameter larger than the outer diameter of said second tubing and smaller than that of said first passage, said second tubing adapted to pass through said first and second passages to an extent limited when said second tubing is in its lowermost position solely by the contact of said second sealing means and said means attached to the lower end of said first tubing.

8. An apparatus for conducting operations in a Well bore, comprising, in combination, a string of first tubing adapted to be lowered into said well bore, a second tubing of fixed length concentrically mounted in the lower end of said first tubing and together therewith forming a first annular space, said second tubing having an internal flush sealing surface and openings at both ends thereof, a third tubing adapted to be concentrically suspended within said first and second tubings and longitudinally moveable therein by means of a wire line, an external annular sealing means exteriorly mounted on the upper end of said third tubing and adapted to come into sealing relation with said sealing surface of said second tubing to seal the upper end of the annular space between said second and third tubings, and means connected to the lower end of said first tubing for sealing the lower end of said first annular space, said last-mentioned means having a passage therein communicating at its upper end with said second tubing and communicating at its lower end with said well bore below said first tubing, said passage having a diameter smaller than the inner diameter of said second tubing and larger than the outer diameter of said third tubing, said third tubing adapted to pass through said passage to an extent limited when said third tubing is in its lowermost position solely by the contact of said annular sealing means and said means attached to the lower end of said first tubing.

9, Apparatus according to claim 8 wherein a wash-over tool is attached to said means connected to the lower end of said first tubing, said wash'over tool having a passage therein in communication with said passage in said means connected to the lower end of said first tubing, said passage in said wash-over tool having a diameter larger than the external diameter of said third tubing to permit the latter to pass therethrough.

10. Apparatus according to claim 8 wherein an overshot tool is connected to said means connected to the lower end of said first tubing, and a wash-over tool is connected to said overshot tool, said 'overshot and wash-over tools having communicating passages therein communicating with said passage in said means attached to the lower end of said first tubing with diameters larger than the outer diameter of said third tubing to permit the latter to pass through said overshot and wash-over tools.

11. Apparatus according to claim 8 wherein said means connected to the lower end of said first tubing has connected thereto wash-over means and fish-attaching means both of which have passages therein to permit said third tubing to pass therethrough.

12. An apparatus for conducting operations in a well bore, comprising, in combination, a first tubing depending within said well bore, a first sealing means mounted in the lower end of said first tubing and providing an annular sealing surface defining a passage in communication with said first tubing, said passage having a diameter smaller than the inner diameter of said first tubing, a second tubing depending within said first tubing and extending through said passage with the lower end of said second tubing terminating at a point below the lower end of said first tubing and said first sealing means, said second tubing having an outer diameter smaller than the inner diameters of said first tubing and said passage, said second tubing having an opening in the upper end thereof in communication with said first tubing and an opening in the lower end in communication with said well bore, a wire line connected to the upper end of said second tubing and adapted to raise and lower the same within said first tubing and said first sealing means, asecond sealing means mounted on the exterior of the upper end of said second tubing and adapted to engage said sealing surface of said first sealing means in sealing relationship, and shoulder means mounted in said first tubing string adjacent the lower end of said sealing surface and adapted to contact said second sealing means and thereby together with said Wire line function as the sole means for limiting the extent said second tubing can terminate below the lower end of said first tubing.

References Cited in the file of this patent UNITED STATES PATENTS 10 Appleby Aug. 27, 1940 Oak Jan. 2, 1945 Stokes Mar. 9, 1954 Wilhoit Dec. 13, 1955 Tausch et a1 Feb. 26, 1957 Kanady Mar. 5, 1957 Moore May 3, 1960 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N00 3,032 118 May 1. .1962

James R, Jackson et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and th at the said Letters Patent should read as corrected below.

Column 7 line 46 after "said" insert tubular Signed and sealed this 28th day of August 1902,

(SEAL) Attest:

ESTON G, JOHNSON DAY ID L. LADD Attesting Officer Commissioner of Patents 

